Oregon Revised Statutes Revenue and Taxation § 311.226

Omitted property shall be deemed assessed and any tax on it shall be deemed imposed in the year or years as to which the property was omitted. Addition of omitted property to the tax roll in the year in which it is discovered shall not be considered in making the determination of the amount of tax imposed in calculating the effect of the tax limitation under section 11b, Article XI of the Oregon Constitution in that year.